This invention relates generally to motorized dampers, and, more particularly, to motorized dampers for use in freezing temperature conditions.
At least one type of motorized damper includes a damper door rotatably mounted in a damper frame having an opening therethrough. An electric motor is coupled to the damper door and positions the damper door in desired positions relative to the damper frame opening. When located in, for example, an air flow path, air flow through the damper can be regulated by positioning the damper door to, for example, a fully closed position substantially preventing airflow through the damper frame opening, a fully open position where airflow through the damper frame opening is substantially unimpeded, and intermediate positions between the fully open and closed positions.
In certain applications, this type of damper is vulnerable to jamming in cold temperature conditions. For example, refrigerators typically employ one or more of these dampers to regulate airflow between a fresh food compartment and a freezer compartment. The damper is opened to introduce cold air from the freezer compartment into the fresh food compartment to regulate fresh food compartment temperature. The temperature differential between the fresh food compartments and humidity in one or both of the compartments can cause moisture to accumulate on the damper door. The moisture runs down the door and permeates a seal between the damper door and the damper frame, and eventually into the motor housing where it may collect on cam surfaces, gears, and other moving parts of the motor mechanism. Freezing temperatures therefore create ice on the motor mechanism that can jam the damper door, or at least impair its ability to be positioned properly. To meet stringent energy and performance requirements, it is important that the dampers be positioned reliably and accurately.